RAILWAY TECHNOLOGY AND INNOVATION DRIVERLESS TRAINS

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1 By Alan Trestour Customer Director, Alstom Transport and Alan De-Reuck Customer Director, Alstom Transport 1. Definition of train Automation The notion of Automatic Train Operation (ATO) defines the operational safety levels against functional requirements needed to help automate train operations. The International Association of Public Transport (UITP) has defined five Grades of Automation (GoA) for trains. The GoA s are defined according to basic functions of train operation and split in operational responsibilities whether it is for humans or the system itself. GoA 0 is a train driver on-sight operation, similar to a tram system running in street traffic, reliant entirely on train driver to manage the system safety. GoA 1 is a train operation where a train driver controls starting and stopping, operation of doors and handling of emergencies or sudden diversions, but with an Automatic Train Protection (speed and signal past at danger protection control). GoA 2 is semi-automatic train operation (STO) where stopping is automated but a driver in the cab starts the train, operates the doors, drives the train if needed and handles emergencies. Many ATO systems are GoA 2. GoA 3 is driverless train operation (DTO) where starting and stopping are automated but a train attendant operates the doors and drives the train in case of emergencies. GoA 4 is unattended train operation (UTO) where starting and stopping, operation of doors and handling of emergencies are fully automated without any on-train staff. 2. History of driverless system and levels of train Automation Figure 2 First Light rail automated transit systems (VAL) Historically, ATO was first used on automated guideway transits and subways which were easier to ensure safe transportation of humans. The name VAL was originally used for this system of operation because it represented the route of the first line Villeneuve d Ascq à Lille (i.e.: Villeneuve d Ascq to Lille) this system was the first fully automated driverless metro in Europe, starting service in 1983 and can cope with unanticipated demand by inserting additional trains into the network as required, remotely from the control centre. The control centre computer system automatically speeds up or slows down trains in order to maintain a timetable. The train length is just 26 metres in length (two linked cars), 2 metres in width and with a passenger capacity of 152 per twin-unit train the VAL trains are smaller in size and mass than traditional suburban trains. They partially make up for their low passenger capacity however by being able to operate at headways of as close as 60 seconds. Figure 1 Grades of Automation 7

2 The advantage of using lightweight trains such as these is that it reduces the cost of building the overall system. Shorter trains require shorter (cheaper to construct) stations whilst lighter-weight railcars require physical infrastructure which is of a lower mass and therefore also less expensive to construct. Most ATO system operators elect to maintain a driver (train operator) to mitigate risks associated with failures or emergencies; however, this operational arrangement is made at the discretion of the train service operator. More recently, modern rail systems are linked with Automatic Train Control (ATC) and in many cases Automatic Train Protection (ATP) where normal controller operations such as route setting and train regulation are carried out by the computer system. An ATO and overlay of ATC/ ATP combined systems work together to maintain a train within a defined tolerance of its timetable. The combined overall system marginally adjusts operating parameters such as the ratio of power to coast when moving and station dwell time, in order to bring a train back to the required timetable slot defined for it. From standalone Speed Code systems to CBTC (Communications Based Train Control) Speed Code systems were first introduced in the 1960s, to manage automatic operations of guided vehicles including light trains. A Speed Code system transmits a signal indication from the interlocking to the train via the rails. This system met the main requirements of operators including: Presentation of a cab-signal on the driver display Full safety from the ATP supervision Driver assistance with ATO operation Some reduction in equipment (only a few back-up line-side signals are required) This technology however has two limitations. Firstly, the train only sees a code for the speed to be reached by the next track circuit section. There the train does not have a view of the track speed profile and the train-running speed is not optimized. Secondly, very short track circuits of 50 metres are required if the trains are to be able to run at short intervals (headway); this makes the implementation of such a system fairly complex with much trackside equipment to be maintained. Figure 3 Typical CBTC System 8

3 The CBTC technology was first developed in the 1980s as an improvement to the previous existing Speed Code systems. Definition of a CBTC system is a continuous, automatic train control system utilizing high-resolution train location determination independent of track circuits; continuous, high-capacity, bidirectional train-to-wayside data communications; train-borne and wayside processors capable of implementing Automatic Train Protection (ATP) functions, as well as optional Automatic Train Operation (ATO) and Automatic Train Supervision (ATS) functions., as defined in the IEEE 1474 standard. 4. Alstom Transport achieved the implementation of a radiobased moving block on a driverless heavy metro in 2003 on the Singapore North-East line, the world s second longest fully underground, automated and driverless, rapid transit line with a waveguide transmission system. 5. The implementation of CBTC to modern radio (compact and standardized), was achieved both by Alstom Transport and Siemens in Beijing for the 2009 Olympics. 3. Drivers, benefits and Risks of driverless metros Modern CBTC technology has been developed in a series of stages from 1980 to today: 1. Bi-directional transmission (train to track, track to train) for moving block was implemented in 1985 using a cable loop placed between the rails (as shown on the photo below) on a medium capacity line in Vancouver. Figure 4 Cable loop 2. Alstom Transport, Siemens and Ansaldo developed the function of transmission of the track in running profile (description of track and speed) to the train in The implementation of CBTC on a driverless heavy metro with transmission by a cable placed between the rails was achieved on Paris Line 14 (METEOR) 9

4 Urban transit systems such as urban rail in large cities are facing continuous increases in ridership demand around the world as a result of urban economic activity encouraging transit in ever increasing numbers to and from within the cities. This increase in urban transit demand is translated by pressures on the system with respect to: Augmentation in capacity of the transit system Higher performances in availability and reliability of the system Increased complexity of the operating environments (such as timetable and resources management) Higher operating costs Benefits of driverless systems There are many benefits for choosing an automated, driverless system. Some of these benefits include: Increasing the capacity Conventional suburban lines are built for a train frequency of between 180 to 200 seconds headways (or 3-3 ½ minutes), which are typically maximum frequencies of train movements during morning and evening peak hours. With a new ATC system in place, additional (virtual) blocks exist between stationary block signals, thus significantly increasing line capacity a typical example being train frequency of 90 seconds achieved on the Moscow Metro with up to 9 million persons travelling on these trains on a daily basis. However, these new blocks can only be used by ATC-operated trains since they are virtual and have no stationary signal associated with them that can be observed by a driver-operated train without ATC equipment. Thus the increased line capacity can only be effectively used after the system has been converted to full ATC operation. Reduced Operating Costs Reduction in Operating cost by controlled energy consumption and optimizing deployment of resources. No driver required. These experienced resources can be trained as service employees, available to passengers inside the carriages and on platforms to look out for disruptions and possible crime, thus increasing the subjective security, supply information and answer passenger queries and other general passenger assistance. Improve safety and passenger satisfaction Former drivers who were behind a closed door before, busy with the operation of the train can be trained for redeployment as key customer service attendants, more visible and responsive to passenger needs. Automatic Train Regulation: Operating flexibility and improved on time running reliability ATC-controlled trains in storage tracks can be activated instantly, making it possible for the line controller to put additional trains into passenger service at a moment s notice when he observes unexpected increases in passenger numbers on the line. The fact that resource notice and central control interface are minimal enables this to be achieved at relatively short notice. Figure 5 Evolution of rail ATC and Interlocking equipment over time 10

5 Securing a driverless system corridor An important consideration for CBTC full UTO systems is that they are generally totally closed systems of operation fully segregated and secure right of ways with controlled access. Generally, this requires building high chain-link fencing along the corridor tracks with CCTV cameras and monitored secured access gates. Perimeter intrusion detection systems linked to the CCTV system are also recommended these provide instantaneous information on the location and nature of the intrusion to the Operating Control Centre (OCC). If at grade road crossings are present, they all need to be replaced by over/under pass for the UTO tracks. If the line runs next to a freight route, specific provision will have to be taken to prevent encroachment secured right of way following a derailment. Operating risks of automatic driverless trains Automated railways work on the basis of the trains collecting information about the line ahead, signals, maximum speeds, train positions etc. as they travel, very much reliant on the robustness of the communications network. Should the communications fail, the system fails bringing operations to a complete stop within the controlled area, as this is the only realistic way of ensuring absolute safety. Where there are railway staff on the trains it is often possible for them to override the no code / automatic stop, but for safety (to reduce the risk of colliding with a train in front especially when in tunnels) when in this emergency mode the trains are normally restricted to a very slow speed. Typically, this will be something like 10mph or 15km/h. If the fault is just that one train has lost the ability to receive the communications signal, then it is usually possible for the train to be driven at this speed to somewhere where it can be taken out of service without blocking the rest of the route. But, realistically at that very slow speed it is inevitable that all other trains behind it (plus the passengers!) will experience significant delays. 4. Driverless systems functionality & Technology enablers for driverless system The main objective of CBTC is to increase capacity by safely reducing the time interval (headway) between trains travelling along the line. Traditional legacy signaling systems were designed to ensure the detection of the trains in discrete sections of the track called blocks. Each block is protected by signals that prevent a train entering an occupied block. Since every block is fixed by the infrastructure, these systems are referred to as fixed block systems. Unlike the traditional fixed block systems, in CBTC systems the protected section for each train is not statically defined by the infrastructure (except for the virtual block technology, with operating appearance of a moving block but still constrained by physical blocks). This can be achieved with the trains continuously communicating their exact position to the equipment in the track by means of a bi-directional link (train to track and track to train); either using inductive loops or radio communication. A trackside computer tracks all trains in the assigned section of line and calculates an appropriate movement authority for each train. As a result, trains are routed continuously and can then run at shorter headways than when driven manually on sight. In fully automated mode, metro trains are driven by the automatic train control (ATC) together with control and protection of the line by interlockings. To this end, the trackside computers are constantly exchanging data with the computers of the higher-level system in the control centre and the computers on board the train by radio (using high frequencies). On board, the Automatic Train Operation (ATO) system replaces the metro driver and controls the train s speed. The ATO computer is continuously monitored and, if necessary, corrected by the Automatic Train Protection (ATP) system which comprises track side and train borne elements. 11

6 Figure 6 Conventional fixed block system Figure 7 Moving block system 12

7 Figure 8 CBTC Communications Network Please refer below for the definitions of the system s elements. Automatic Train Protection (ATP): The ATP system (includes on board and trackside components) is responsible for the basic safety function. It avoids collisions, red signal overrunning (SPAD) and exceeding speed limits by applying brakes automatically. A line equipped with ATP corresponds (at least) to a GoA1. Automatic Train Operation (ATO): Ensures partial or complete automatic train piloting and driverless functionalities. The ATO system performs all the functions of the driver, except for door closing. The driver only needs to close the doors, and if the way is clear, the train will automatically proceed to the next station. This corresponds to a GoA2. Many newer systems are completely computer controlled; however, most system operators still elect to maintain a driver, or a train attendant of some kind to mitigate risks associated with failures or emergencies. This corresponds to a GoA3. Automatic Train Control (ATC): It performs automatically normal controller operations such as route setting and train regulation. The ATO and ATP systems work together to maintain a train within a defined tolerance of its prescribed timetable. The combined system will marginally adjust operating parameters such as the ratio of power to coast when moving and station dwell time, in order to bring the train back to the timetable slot defined for it. There is no driver, and no staff assigned to accompany the train, corresponding to a GoA4. ATC equipment is made of: train-borne equipment, including: UNIVIC computer which implements both ATP and ATO functions and interface with other onboard ATC equipment and train equipment (traction, doors control, emergency brake ) on a redundant network (2 computers on trains). Beacon antenna, which sends an energizing signal to activate the balises on the track that reads messages sent back to the balise, detects the precise balise location and sends information to the UNIVIC. 13

8 Odometer, which measures the wheel rotations for calculation of distance and speed by the UNIVIC. DMI, which in the event of manual driving will present the train control indicators to the driver in a backup operation included degraded model (in UTO configuration). Track side equipment, including: Zone Controller (ZC), which calculates the right location and movement for each train and supervises the PSD. Line Controller (LC), which provides the TSR on request and line data update permanently to each train. Balise which provides localization information to the train, and are placed every 200m along the track. Finally, two other key components of the CTBC are the ATS (Automatic Train Supervision) and the DCS (Data Communications System). The DCS allows the overall system to have a continuous communication between all parts of the CBTC system and can also provide telecommunication services (radio and LAN networks) for non-vital signalling functions such as PIS and CCTV. The DCS network is configured fully redundant and uses standard protocol between all sub-systems. The ATS is a traffic management function, and is dedicated to the overall monitoring of all signalling and train operation data and to the management and supervision of the traffic regulation algorithms including scheduled timetable and headway. It automatically issues commands on track routing and assigns new operational missions to trains. The operator can also intervene in event of a degraded operation to move the train manually (via a joystick). 5. High level of Safety on driverless trains: There is no compromise on the safety of passengers on driverless systems, as summarized by the following points: In the event of an emergency call or emergency brake activated by a passenger, the OCC (Operations Control Centre) will obtain direct audible and visual communication link thanks to full passenger CCTV surveillance inside trains. Therefore, each incident is monitored live and appropriate intervention can be triggered quickly and effectively. In the event of a fire break out inside the train, smoke detector and temperature sensors will trigger an instant alarm in the OCC and the train is stopped automatically at the next station, where personnel can investigate the cause of the fire alarm. A public-address system in the passenger area serves for the announcement of operational and traffic information. If required, passengers can contact the OCC at any time via the emergency call point. A passenger who triggers an alarm is connected directly via an audio visual radio. Visual and audible signals announce closing of passenger doors on the train. The train doors are interlocked with Platform Screen Doors (PSD), by means of flashing light at the doors as well as a beeping sound. The information is also relayed to persons of impaired vision and hearing. The above functions combined together with the speed control, monitoring and train spacing protection make the driverless trains one of the safest modern transport systems. The DCS allows the overall system to have a continuous communication between all parts of the CBTC system and can also provide telecommunication services (radio and LAN networks) for non-vital signalling functions such as PIS and CCTV. 14

9 AMSTERDAM 5 LINES BEIJING AIRPORT EXPRESS BEIJING L1 & L2 TORONTO YUS LINE LILLE L1 LAUSANNE M2 WUHAN L2 & L4 BEIJING L6 BEIJING FANGSHAN & L9 MEXICO L12 MALAGA L1 & L2 MILAN L1 DUBAI AL - SAFOOH LINE RIYADH 3 LINES SHANGHAI L10 WUXI L1 & L2, NINGBO L1 KUNMING L1 SHENZHEN L2 & L5 SHANGHAI L12 & L13 & L16 GUANGZHOU L6 TAICHUNG HONG KONG SIL (E) PANAMA L1 SINGAPORE NORTH EAST LINE SINGAPORE CIRCLE LINE SAO PAULO L1 & L2 & L3 SANTIAGO L1 Radio CBTC Reference Renovation Driverless Figure 9 Alstom Reference Sites 6. Alstom s driverless systems around the world Through its cutting-edge information solutions, Alstom brings operators the means to ensure the transport of passengers in total safety and fluidity, optimising the capacity of urban lines. Alstom provides cities all over the world with its CBTC Urbalis signalling system, which represents a footprint of around 25% of global CBTC solutions deployed worldwide. This range offers comprehensive and upgradeable signalling solutions and guaranteed reliability, safety and security of the train operations. All four different grades of signalling control automation from GoA 1 (ATP) to full GoA 4 (UTO) can be offered with the Urbalis product range, and there is a solution adapted to each metro service operating requirement. With 9 fully UTO metro system projects awarded over the last fourteen years (including Sydney Metro Northwest), Alstom is constantly striving to innovate in the field of metro driverless solutions. 15

10 City Line/system New line / Rev / Ext Award Year Commissioning No Lines km km at grade km tunnel km elevated No of trains No of stations Singapore North-East Line New Line Singapore Circle Line New Line Lausanne m2 Revamping Shanghai Shanghai L 10 TIS SIG New Line Hong Kong SIL (E) New Line Taichung Green Line New Line Lille Line 1 renovation Revamping Riyadh Orange Purple Yellow Lines New Line Figure 10 Alstom s URBALIS range CBTC deployment reference for UTO (full driverless automation) on metro lines across the world (excludes Sydney awarded in 2014) Paper sources: 1. UITP METRO AUTOMATION FACTS, FIGURES AND TREND 2. Observatory of Automated Metros home page: 3. ALSTOM Urbalis 400 product range description (Alstom copyright) 4. ALSTOM CBTC RANGE IRSE presentation June